Research and development are being undertaken in relation to data sharing systems for diffusing/sharing data among a plurality of communication nodes (see NPL 1, for example). Data transmitted from a certain communication node are received by a peripheral communication node, and the reception node transmits the received data repeatedly at periodic intervals. As a result, the data can be propagated through the system. In a system where the communication nodes are mobile, such as a vehicle-to-vehicle network, the communication nodes transmit the data repeatedly while moving, and therefore the data can be propagated over a wider range.
In this type of data sharing system, it is desirable to be able to transmit transmission of data that are no longer required efficiently. PTL 1 proposes implementing an illegality check or the like using a central server to eliminate distribution of illegal content on a peer-to-peer (P2P) network. Further, PTL 2 proposes setting access rights in order to limit a data sharing range when information is uploaded to a P2P network, and also mentions stopping data distribution and data deletion following transmission.